From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B91B2C35247 for ; Wed, 5 Feb 2020 18:21:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C3172192A for ; Wed, 5 Feb 2020 18:21:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728053AbgBESVt (ORCPT ); Wed, 5 Feb 2020 13:21:49 -0500 Received: from mga14.intel.com ([192.55.52.115]:20937 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727797AbgBESU3 (ORCPT ); Wed, 5 Feb 2020 13:20:29 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Feb 2020 10:20:27 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,406,1574150400"; d="scan'208";a="279447794" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by FMSMGA003.fm.intel.com with ESMTP; 05 Feb 2020 10:20:27 -0800 From: Yu-cheng Yu To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , x86-patch-review@intel.com Cc: Yu-cheng Yu Subject: [RFC PATCH v9 13/27] x86/mm: Shadow Stack page fault error checking Date: Wed, 5 Feb 2020 10:19:21 -0800 Message-Id: <20200205181935.3712-14-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20200205181935.3712-1-yu-cheng.yu@intel.com> References: <20200205181935.3712-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a page fault is triggered by a Shadow Stack (SHSTK) access (e.g. CALL/RET) or SHSTK management instructions (e.g. WRUSSQ), then bit[6] of the page fault error code is set. In access_error(), verify a SHSTK page fault is within a SHSTK memory area. It is always an error otherwise. For a valid SHSTK access, set FAULT_FLAG_WRITE to effect copy-on-write. Signed-off-by: Yu-cheng Yu --- arch/x86/include/asm/traps.h | 2 ++ arch/x86/mm/fault.c | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h index 7ac26bbd0bef..8023d177fcd8 100644 --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -169,6 +169,7 @@ enum { * bit 3 == 1: use of reserved bit detected * bit 4 == 1: fault was an instruction fetch * bit 5 == 1: protection keys block access + * bit 6 == 1: shadow stack access fault */ enum x86_pf_error_code { X86_PF_PROT = 1 << 0, @@ -177,5 +178,6 @@ enum x86_pf_error_code { X86_PF_RSVD = 1 << 3, X86_PF_INSTR = 1 << 4, X86_PF_PK = 1 << 5, + X86_PF_SHSTK = 1 << 6, }; #endif /* _ASM_X86_TRAPS_H */ diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 304d31d8cbbc..9c1243302663 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1187,6 +1187,17 @@ access_error(unsigned long error_code, struct vm_area_struct *vma) (error_code & X86_PF_INSTR), foreign)) return 1; + /* + * Verify X86_PF_SHSTK is within a Shadow Stack VMA. + * It is always an error if there is a Shadow Stack + * fault outside a Shadow Stack VMA. + */ + if (error_code & X86_PF_SHSTK) { + if (!(vma->vm_flags & VM_SHSTK)) + return 1; + return 0; + } + if (error_code & X86_PF_WRITE) { /* write, present and write, not present: */ if (unlikely(!(vma->vm_flags & VM_WRITE))) @@ -1344,6 +1355,13 @@ void do_user_addr_fault(struct pt_regs *regs, perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); + /* + * If the fault is caused by a Shadow Stack access, + * i.e. CALL/RET/SAVEPREVSSP/RSTORSSP, then set + * FAULT_FLAG_WRITE to effect copy-on-write. + */ + if (hw_error_code & X86_PF_SHSTK) + flags |= FAULT_FLAG_WRITE; if (hw_error_code & X86_PF_WRITE) flags |= FAULT_FLAG_WRITE; if (hw_error_code & X86_PF_INSTR) -- 2.21.0 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yu-cheng Yu Subject: [RFC PATCH v9 13/27] x86/mm: Shadow Stack page fault error checking Date: Wed, 5 Feb 2020 10:19:21 -0800 Message-ID: <20200205181935.3712-14-yu-cheng.yu@intel.com> References: <20200205181935.3712-1-yu-cheng.yu@intel.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200205181935.3712-1-yu-cheng.yu@intel.com> Sender: linux-kernel-owner@vger.kernel.org To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit Cc: Yu-cheng Yu List-Id: linux-api@vger.kernel.org If a page fault is triggered by a Shadow Stack (SHSTK) access (e.g. CALL/RET) or SHSTK management instructions (e.g. WRUSSQ), then bit[6] of the page fault error code is set. In access_error(), verify a SHSTK page fault is within a SHSTK memory area. It is always an error otherwise. For a valid SHSTK access, set FAULT_FLAG_WRITE to effect copy-on-write. Signed-off-by: Yu-cheng Yu --- arch/x86/include/asm/traps.h | 2 ++ arch/x86/mm/fault.c | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h index 7ac26bbd0bef..8023d177fcd8 100644 --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -169,6 +169,7 @@ enum { * bit 3 == 1: use of reserved bit detected * bit 4 == 1: fault was an instruction fetch * bit 5 == 1: protection keys block access + * bit 6 == 1: shadow stack access fault */ enum x86_pf_error_code { X86_PF_PROT = 1 << 0, @@ -177,5 +178,6 @@ enum x86_pf_error_code { X86_PF_RSVD = 1 << 3, X86_PF_INSTR = 1 << 4, X86_PF_PK = 1 << 5, + X86_PF_SHSTK = 1 << 6, }; #endif /* _ASM_X86_TRAPS_H */ diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 304d31d8cbbc..9c1243302663 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1187,6 +1187,17 @@ access_error(unsigned long error_code, struct vm_area_struct *vma) (error_code & X86_PF_INSTR), foreign)) return 1; + /* + * Verify X86_PF_SHSTK is within a Shadow Stack VMA. + * It is always an error if there is a Shadow Stack + * fault outside a Shadow Stack VMA. + */ + if (error_code & X86_PF_SHSTK) { + if (!(vma->vm_flags & VM_SHSTK)) + return 1; + return 0; + } + if (error_code & X86_PF_WRITE) { /* write, present and write, not present: */ if (unlikely(!(vma->vm_flags & VM_WRITE))) @@ -1344,6 +1355,13 @@ void do_user_addr_fault(struct pt_regs *regs, perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); + /* + * If the fault is caused by a Shadow Stack access, + * i.e. CALL/RET/SAVEPREVSSP/RSTORSSP, then set + * FAULT_FLAG_WRITE to effect copy-on-write. + */ + if (hw_error_code & X86_PF_SHSTK) + flags |= FAULT_FLAG_WRITE; if (hw_error_code & X86_PF_WRITE) flags |= FAULT_FLAG_WRITE; if (hw_error_code & X86_PF_INSTR) -- 2.21.0 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Yu-cheng Yu Subject: [RFC PATCH v9 13/27] x86/mm: Shadow Stack page fault error checking Date: Wed, 5 Feb 2020 10:19:21 -0800 Message-ID: <20200205181935.3712-14-yu-cheng.yu@intel.com> In-Reply-To: <20200205181935.3712-1-yu-cheng.yu@intel.com> References: <20200205181935.3712-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-doc-owner@vger.kernel.org To: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , x86-patch-review@intel.com Cc: Yu-cheng Yu List-ID: Message-ID: <20200205181921.TcPmXAlsWqrZEQ3YeFScFeH5Iqk-D22nq52XDVZTU2Y@z> If a page fault is triggered by a Shadow Stack (SHSTK) access (e.g. CALL/RET) or SHSTK management instructions (e.g. WRUSSQ), then bit[6] of the page fault error code is set. In access_error(), verify a SHSTK page fault is within a SHSTK memory area. It is always an error otherwise. For a valid SHSTK access, set FAULT_FLAG_WRITE to effect copy-on-write. Signed-off-by: Yu-cheng Yu --- arch/x86/include/asm/traps.h | 2 ++ arch/x86/mm/fault.c | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h index 7ac26bbd0bef..8023d177fcd8 100644 --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -169,6 +169,7 @@ enum { * bit 3 == 1: use of reserved bit detected * bit 4 == 1: fault was an instruction fetch * bit 5 == 1: protection keys block access + * bit 6 == 1: shadow stack access fault */ enum x86_pf_error_code { X86_PF_PROT = 1 << 0, @@ -177,5 +178,6 @@ enum x86_pf_error_code { X86_PF_RSVD = 1 << 3, X86_PF_INSTR = 1 << 4, X86_PF_PK = 1 << 5, + X86_PF_SHSTK = 1 << 6, }; #endif /* _ASM_X86_TRAPS_H */ diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 304d31d8cbbc..9c1243302663 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1187,6 +1187,17 @@ access_error(unsigned long error_code, struct vm_area_struct *vma) (error_code & X86_PF_INSTR), foreign)) return 1; + /* + * Verify X86_PF_SHSTK is within a Shadow Stack VMA. + * It is always an error if there is a Shadow Stack + * fault outside a Shadow Stack VMA. + */ + if (error_code & X86_PF_SHSTK) { + if (!(vma->vm_flags & VM_SHSTK)) + return 1; + return 0; + } + if (error_code & X86_PF_WRITE) { /* write, present and write, not present: */ if (unlikely(!(vma->vm_flags & VM_WRITE))) @@ -1344,6 +1355,13 @@ void do_user_addr_fault(struct pt_regs *regs, perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); + /* + * If the fault is caused by a Shadow Stack access, + * i.e. CALL/RET/SAVEPREVSSP/RSTORSSP, then set + * FAULT_FLAG_WRITE to effect copy-on-write. + */ + if (hw_error_code & X86_PF_SHSTK) + flags |= FAULT_FLAG_WRITE; if (hw_error_code & X86_PF_WRITE) flags |= FAULT_FLAG_WRITE; if (hw_error_code & X86_PF_INSTR) -- 2.21.0